Conventionally, a gasket configured by using a metal mesh member and expanded graphite has been known (for example, see Patent Literature 1). Usually, a method of producing a gasket of this kind includes a material preparing step, a composite body forming step, a tubular body forming step, and the compression molding step.
In the material preparing step, a metal mesh member and expanded graphite are prepared. In the composite body forming step, a long belt-like composite body in which the expanded graphite and the metal mesh member overlap with one another is formed. In the tubular body forming step, the composite body is spirally wound so as to form a tubular body in a multiply wound state in which the axial direction coincides with the short-side direction of the composite body.
In the compression molding step, the tubular body is compression molded in the axial direction in order to obtain a gasket. Specifically, in a state where a stationary die and a movable die which is reciprocable to and from the stationary die are used, the tubular body is loaded between inner and outer stationary dies so that the tubular body is fitted onto the shaft-like inner stationary die. Thereafter, the movable die is pressed in the gap between the inner stationary die and the outer stationary die, the tubular body being located in the gap.
In the above-described method of producing a gasket, when the compression molding step is to be performed, however, the width dimension in the axial direction of the tubular body is substantially constant over the whole circumference (i.e., the width dimension in the short-side direction of the composite body is substantially constant over the whole length). When an external force in the compression direction is applied to the tubular body (composite body), therefore, end portions (free end portions) of the tubular body are excessively deformed, and burrs are easily formed on the gasket which is obtained after the compression molding step.